1986 4wheel drive with 3inch body lift, 4 inch susp. lift with a 305 chev. 350turbo trans. with shift kit. on 35's has short headers. When driving on pavement at 55-60 she bucks like one rear tire spin's then the other. felt like back of truck was loose or rocking side to side. There is no noise when this happens. What causes this to happen??

Today we whent mudding and man this baby fly's.

 

Is the rear 3rd in good shape? It could be the ring gear is missing some teeth.

 

Is the rear 3rd in good shape?

can you decribe this please??

 

Did he buy the truck already set up like that? Not many people do a lift and V8 swap and have no knowlege of things like gears. Do a search for 3rd member removal, and pull the third member out and have a look at the gears. Also look for obvious things - look carefully at the rear springs, is one broken, or a spring hangar or shackle? Is there a bent rim? A rear tire (or both) badly out of balance? Another thing to look at is if the driveshaft u-joints are in phase, but that would "buck" it would howl and vibrate.

 

he bought the truck like that. Today after our mudding trip i checked the susp. it looks alright. I grabed bed side and rocked the truck the only movement was tire roll. no bent rims i watched him fry al 4 tires. I did find out that we tore the left side motor mount in half! Truck has IFSusp.

 

He put new rear shocks on it said it helped a little. would traction bars help???What would happen if we put in solid steel motor mounts???

 

Solid steel motor mounts? First off, the truck would vibrate so badly the windows would roll themselves down, the CD player wouldnt' work, your teeth would fall out and your ba.. backside would get numb. Solid mounts are for zillion horsepower drag racers, and even those guys don't like em - that's why they try to get down the strip as fast as they can....

 

But I bet if you fix that busted mount the "bucking" goes away.... :pat:

 

What can be done to keep the stock motor mount rubber from tearing again ??

 

Well, my first thought goes like this: There are literall hundreds of thousands of V8 vehicles out there going strong (I own a couple of them in fact) and the mounts aren't breaking. So, maybe put a pair of good quality brand new mounts in there, (be sure they are aligned properly,) and don't worry, be happy.